Merge branch '3.0'

* 3.0: (28 commits)
  [Console] Fix an autocompletion question helper issue with non-sequentially indexed choices
  [Process] Fix pipes handling
  [Finder] Partially revert #17134 to fix a regression
  Mentioned the deprecation of deep parameters in UPGRADE files
  [HttpKernel] Fix mem usage when stripping the prod container
  [Filesystem] Fix false positive in ->remove()
  [Filesystem] Cleanup/sync with 2.3
  [Validator] Fix the locale validator so it treats a locale alias as a valid locale
  [HttpFoundation] Fix transient test
  [HttpFoundation] Add a dependency on the mbstring polyfill
  [2.7] update readme files for new components
  add readme files where missing
  [2.8] update readme files for new components
  fix lowest TwigBridge deps versions
  reference form type by name on Symfony 2.7
  [EventDispatcher] fix syntax error
  Don't use reflections when possible
  Don't use reflections when possible
  [Form] Update form tests after the ICU data update
  [Intl] Update tests and the number formatter to match behaviour of the intl extension
  ...

Conflicts:
	src/Symfony/Component/Ldap/README.md
	src/Symfony/Component/Security/Core/README.md
	src/Symfony/Component/Security/Csrf/README.md
	src/Symfony/Component/Security/Http/README.md

Author: nicolas-grekas

Tests/Normalizer/GetSetMethodNormalizerTest.php

@@ -615,6 +615,11 @@ public static function setStaticObject($object)
     {
         self::$staticObject = $object;
     }
+
+    protected function getPrivate()
+    {
+        throw new \RuntimeException('Dummy::getPrivate() should not be called');
+    }
 }
 
 class GetConstructorDummy